1. Field of the Invention
The present invention relates to a packet service in an integrated service digital network (ISDN), more particularly, to a method for management of logical channels for a packet service.
An ISDN is meant to integrate all existing services on packet networks, telephone networks, and telex networks into a single whole. Various studies are underway on realization of such a network. Among these, the present invention refers in particular to a D-channel and/or B-channel packet handling method in ISDN. At the present time, a packet handler is used for packet processing interworking with main exchange via the common channel signaling method.
Various questions arise when considering how to completely integrate packet switching service in an ISDN. Among these, the present invention takes up as one of its topics the provision of a number of pieces of data terminal equipment (DTE) at each subscriber access interface.
2. Description of the Related Art
When seen from an exchange, logical channel number areas (LCN) are managed for each subscriber independently. That is, in the ISDN, LCN's are allotted in correspondence to the subscribers, e.g., 10 LCN's for one subscriber and 15 LCN's for another. The exchange side does not maintain information on how many LCN's are allotted to individual pieces of data terminal equipment in the case of each subscriber being provided with a number pieces of data terminal equipment. The omission by the exchange side of such management of characteristics of individual terminals is approved in CCITT recommendations. The exchange side need not know what the terminal equipment on the subscriber side is comprised of. In the final analysis, it is impossible to separately define logical channels for each data terminal equipment and impossible to allot the optimal number of ICN's for each data terminal equipment under the same access interface. This is disadvantageous when shifting to a full-scale ISDN and when the pieces of data terminal equipment of each subscriber become increasingly complicated.
Further, each data terminal equipment must have the same number of LCN's and the "logical channel range" as spoken of in the CCITT recommendation X.25 for determining methods of use of LCN's must also be the same.